In this study, an experimental setup for the evaluation of a two-stage anaerobic digestion has been developed: a laboratory-scale apparatus was assembled employing solid potatoes as energy crops. Two coupled 5-litre batch-fed stirred reactors, one for the hydrolytic-acidogenic step and one for the acetogenic-methanogenic step, kept at mesophilic temperature (308.1 K), were adopted. Evaluated in the first acidogenic reactor was the influence of fermentative yeast (Saccharomyces Cerevisiae) on the degree of hydrolysation and on the acidification rate of the vegetable substrate. All runs were performed without the addition of chemicals. Samples of hydrolysed substrate were sent to the second methanogenic bioreactor, fed with an industrial anaerobic sludge and selected lyophilized anaerobic bacteria, in order to evaluate the methane yield of the produced biogas and the specific methanogenic activity (SMA). The whole procedure was repeated simulating an anaerobic sequencing batch reactor (ASBR) process.
